What are PyISAPI_loader.dll Error Messages?

Dynamic Link Library PyISAPI_loader.dll Errors

PyISAPI_loader.dll is considered a type of Dynamic Link Library (DLL) file. Dynamic Link Library files, like PyISAPI_loader.dll, are essentially a "guide book" that stores information and instructions for executable (EXE) files - like calibre-eject.exe - to follow. These files were created so that multiple programs (eg. Calibre) could share the same PyISAPI_loader.dll file, saving valuable memory allocation, therefore making your computer run more efficiently.

Unfortunately, what makes DLL files so convenient and efficient, also makes them extremely vulnerable to problems. If something happens to a shared DLL file, either it goes missing or gets corrupted in some way, it can generate a "runtime" error message. Runtime is pretty self-explanatory; it means that these errors are triggered when PyISAPI_loader.dll is attempted to be loaded either when Calibre is starting up, or in some cases already running. Some of the most common PyISAPI_loader.dll errors include:

• Access Violation at address - PyISAPI_loader.dll.
• PyISAPI_loader.dll could not be found.
• Cannot find C:\Program Files (x86)\Calibre2\app\bin\PyISAPI_loader.dll.
• Cannot register PyISAPI_loader.dll.
• Cannot start Calibre. A required component is missing: PyISAPI_loader.dll. Please install Calibre again.
• Failed to load PyISAPI_loader.dll.
• The application has failed to start because PyISAPI_loader.dll was not found.
• The file PyISAPI_loader.dll is missing or corrupt.
• This application failed to start because PyISAPI_loader.dll was not found. Re-installing the application may fix this problem.

Your PyISAPI_loader.dll file could be missing due to accidental deletion, uninstalled as a shared file of another program (shared with Calibre), or deleted by a malware infection. Furthermore, PyISAPI_loader.dll file corruption could be caused from a power outage when loading Calibre, system crash while loading PyISAPI_loader.dll, bad sectors on your storage media (usually your primary hard drive), or quite commonly, a malware infection. Thus, it's critical to make sure your anti-virus is kept up-to-date and scanning regularly.

How to Fix PyISAPI_loader.dll Errors in 3 Steps (Time to complete: ~5-15 minutes)

If you're encountering one of the error messages above, follow these troubleshooting steps to resolve your PyISAPI_loader.dll issue. These troubleshooting steps are listed in the recommended order of execution.

To begin System Restore (Windows XP, Vista, 7, 8, and 10):

1. Hit the Windows Start button
2. When you see the search box, type "System Restore" and press "ENTER".
3. In the search results, find and click System Restore.
4. Please enter the administrator password (if applicable / prompted).
5. Follow the steps in the System Restore Wizard to choose a relevant restore point.
6. Restore your computer to that backup image.

If the Step 1 fails to resolve the PyISAPI_loader.dll error, please proceed to the Step 2 below.

You can uninstall Calibre software by following these instructions (Windows XP, Vista, 7, 8, and 10):

1. Hit the Windows Start button
2. In the search box, type "Uninstall" and press "ENTER".
3. In the search results, find and click "Add or Remove Programs"
4. Find the entry for Calibre 4.2.0 and click "Uninstall"
5. Follow the prompts for uninstallation.

After the software has been fully uninstalled, restart your PC and reinstall Calibre software.

If this Step 2 fails as well, please proceed to the Step 3 below.

Calibre 4.2.0

Kovid Goyal

When the first two steps haven't solved your issue, it might be a good idea to run Windows Update. Many PyISAPI_loader.dll error messages that are encountered can be contributed to an outdated Windows Operating System. To run Windows Update, please follow these easy steps:

1. Hit the Windows Start button
2. In the search box, type "Update" and press "ENTER".
3. In the Windows Update dialog box, click "Check for Updates" (or similar button depending on your Windows version)
4. If updates are available for download, click "Install Updates".
5. After the update is completed, restart your PC.

If Windows Update failed to resolve the PyISAPI_loader.dll error message, please proceed to next step. Please note that this final step is recommended for advanced PC users only.

If Those Steps Fail: Download and Replace Your PyISAPI_loader.dll File (Caution: Advanced)

If none of the previous three troubleshooting steps have resolved your issue, you can try a more aggressive approach (Note: Not recommended for amateur PC users) by downloading and replacing your appropriate PyISAPI_loader.dll file version. We maintain a comprehensive database of 100% malware-free PyISAPI_loader.dll files for every applicable version of Calibre. Please follow the steps below to download and properly replace you file:

1. Locate your Windows operating system version in the list of below "Download PyISAPI_loader.dll Files".
2. Click the appropriate "Download Now" button and download your Windows file version.
3. Copy this file to the appropriate Calibre folder location:
   
   Windows 10: C:\Program Files (x86)\Calibre2\app\bin\
   
4. Restart your computer.

If this final step has failed and you're still encountering the error, you're only remaining option is to do a clean installation of Windows 10.

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